Design characteristics for byproduct fatty acid recovery

This investigation was undertaken in order to determine the characteristics of crude fatty acids, recovered from the resin soap wastes of kraft pulp manufacture, so that efficient distillation units may be designed for distillation of the crude fatty acids.

It was found that the crude fatty acids could be distilled at a maximum absolute pressure of 7 m.m., and at a temperature range of 400° to 520ºF. At this temperature range approximately 70% of the total can be recovered as distillate without impairing the quality of the distillate. The remaining 30% is removed as pitch.

It was found that when 70% of the total has been distilled approximately 85% of the fatty acids and 80% of the abietic acid originally present have been recovered

Crude fatty acids corroded to a marked extent all of the feasible alloys and metals of construction with the exception of the stainless steel containing not less than 20% chromium and not less than 9% nickel.

It was found that the most suitable alloy was a chromium-nickel-iron alloy containing 29% chromium and 9% nickel, the balance being iron.